Herbicide resistance in Australian grain cropping

Herbicides are a major input cost for grain growers but are an essential tool in the management of weeds.

The challenge

Herbicides are the dominant weed management tactic in grain cropping systems. However, the effectiveness of this as a tactic can be variable due to the ability of susceptible weeds to develop resistance to these herbicides. There are currently 47 weed species which have confirmed herbicide resistance status in Australia.

These are resistant to 10 different Modes of Action. Thirty of these species are known to be grain cropping weeds. It has been estimated that Australian grain growers spend an extra $8.24/ha to control herbicide resistant weeds, over$187M per annum.

Project name: Determining the incidence of herbicide resistance in Australian grain cropping (2020 -2024)

Funding Grains Research and Development Corporation (GRDC) $2.814M

Our response

Understanding the incidence and extent of herbicide resistant weeds can have multiple benefits. It identifies where investment is required to develop strategies to manage and prevent resistance.

Random surveying at a national scale is best to achieve this overall picture. In addition, if communicated effectively, increases industry awareness leading to increased resistance testing by advisers and growers through commercial services. This allows optimal weed management decisions to be made.

In conjunction with the random surveys the Gulbali Institute also operates a commercial herbicide resistance testing service, screening specific weed populations for producers.

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The goal

The Australian grain growing region was surveyed in 2021-2022 to determine the resistance status of major winter and summer grain cropping weeds to key herbicides.

Data from these and historic surveys will be used to create a consolidated Australian grain herbicide resistance data set.

The development and delivery of a communications package nationally to inform industry of the herbicide resistance status of key cropping weeds and the benefits of grower herbicide resistance

  • To help producers avoid using chemicals that are no longer effective.
  • To limit the development and spread of herbicide resistance.
  • To inform research into integrated weed management practices.

For 5% of growers  to have reduced the additional cost of managing herbicide resistant weeds by 10% through increased knowledge of the herbicide resistance status of key weeds of grain cropping systems in Australia.

Our team

Principal scientist

Our research team

Allison Chambers
Technical Officer

Key research publications

Broster, J. C., Boutsalis, P., Gill, G. S., & Preston, C. (2023). The frequency of herbicide resistance in wild oats (Avena spp.), brome grass (Bromus spp.) and barley grass (Hordeum spp.) as determined by random surveys across south-eastern Australia. Crop and Pasture Science, Online early, https://doi.org/10.1071/CP22386

Broster, J. C., Chambers, A., Weston, L. A., & Walsh, M. J. (2022). Annual Ryegrass (Lolium rigidum), Wild Oats (Avena spp.) and Sowthistle (Sonchus oleraceus) are the most commonly occurring weeds in New South Wales cropping fields. Agronomy, 12(12), [2914]. https://doi.org/10.3390/agronomy12122914

Broster, J. C., Boutsalis, P., Gill, G. S., & Preston, C. (2022). The extent of herbicide resistance in Lolium rigidum Gaud. (annual ryegrass) across south-eastern Australia as determined from random surveys. Crop and Pasture Science, 73(11), 1308-1317. https://doi.org/10.1071/CP21753

Squires, C. C., Coleman, G. R. Y., Broster, J. C., Preston, C., Boutsalis, P., Owen, M. J., Jalaludin, A., & Walsh, M. J. (2021). Increasing the value and efficiency of herbicide resistance surveys. Pest Management Science, 77(9), 3881-3889. https://doi.org/10.1002/ps.6333

Aves, C., Broster, J., Weston, L. A., Gill, G. S., & Preston, C. (2020). Conyza bonariensis (flax-leaf fleabane) resistant to both glyphosate and ALS inhibiting herbicides innorth-eastern Victoria. Crop and Pasture Science, 71(9), 864-871. https://doi.org/10.1071/CP19537

Kelly, J., Chambers, A., Weston, P., Brown, W., Robinson, W., Broster, J., & Weston, L. A. (2020). The impact of herbicide application and defoliation on barley grass (Hordeum murinum subsp. glaucum) management in mixed pasture legumes. Agronomy, 10(5), 1-23. [671]. https://doi.org/10.3390/agronomy10050671

Broster, J. C., Pratley, J. E., Ip, R., Ang, L., & Seng, K. P. (2019). A quarter of a century of monitoring herbicide resistance in Lolium rigidum in Australia. Crop and Pasture Science, 70(3), 283-293. https://doi.org/10.1071/CP18584

Broster, J. C., Pratley, J. E., Ip, R. H. L., Ang, L., & Seng, K. P. (2019). Cropping practices influence incidence of herbicide resistance in annual ryegrass (Lolium rigidum) in Australia. Crop and Pasture Science, 70(1), 77-84. https://doi.org/10.1071/CP18355

Broster, J., & Chambers, A. (2019). The extent of herbicide resistance in rice crops of southern New South Wales. In Cells to Satellites: Proceedings of the 19th Australian Society of Agronomy Conference (pp. 1-4). Australian Society of Agronomy. http://agronomyaustraliaproceedings.org/images/sampledata/2019/2019ASA_Broster_John_284.pdf

Walsh, M. J., Broster, J., & Condon, G. (2019). Weed control in Australian grain production systems, now and into the future. In Grains research update: Boosting profitability - resilient solutions (pp. 221-227). (GRDC Grains Research Update). Grains Research and Development Corporation. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2019/02/weed-control-in-australian-grain-production-systems,-now-and-into-the-future2

Walsh, M. J., Broster, J., Chauhan, B., Rebetzke, G. J., & Pratley, J. (2019). Weed control in cropping systems – past lessons and future opportunities. In J. Pratley, & J. Kirkegaard (Eds.), Australian agriculture in 2020: From conservation to automation (pp. 153-172). Australian Society of Agronomy. http://agronomyaustraliaproceedings.org/index.php/special-publications

Broster, J., & Chambers, A. (2019). Weeds present in rice crops of southern New South Wales. In Proceedings of the 19th Australian Agronomy Conference (pp. 1-4). Australian Society of Agronomy. http://agronomyaustraliaproceedings.org/images/sampledata/2019/2019ASA_Broster_John_285.pdf

Broster, J., Chambers, A., Weston, L., & Walsh, M. J. (2018). Herbicide and weed management - latest research. In Proceedings from the GRDC Update events series (pp. 107-113). GRDC. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/02/herbicide-and-weed-management-latest-research2

Jalaludin, A., Widderick, M. J., Broster, J., & Walsh, M. J. (2018). Glyphosate and 2,4-D amine resistance in common sowthistle (Sonchus oleraceus) and fleabane (Conyza bonariensis) in the northern grain growing region of Australia. 139-139. Abstract from 21st Australasian Weeds Conference (2018), Sydney, New South Wales, Australia.

Broster, J., Chambers, A., Weston, L., & Walsh, M. J. (2018). Herbicide and weed management - latest research. In Proceedings from the GRDC Update events series (pp. 107-113). GRDC. https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/02/herbicide-and-weed-management-latest-research2

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